This invention relates generally to spherical bearings and more particularly to dual load path spherical bearings and dual load path rod end bearings.
A primary concern of designers of aircraft and other public transportation vehicles is safety. Of particular concern are components with the capacity for catastrophic failure. In fact, Federal Air Regulations Part 23.1309 and Part 25.1309 require that the occurrence of any failure condition which would prevent the continued safe flight and landing of an airplane is extremely improbable.
Current spherical and rod end bearing designs are susceptible to single point failures in: the antifriction feature, the bearing ball (uni-ball), and the bearing race. Rod end bearings are additionally susceptible to single point failures in the bearing coupling shaft and the threads of the bearing coupling shaft. Current attempts to conform spherical and rod end bearing designs to acceptable safety standards including the aforementioned Federal Regulations include using multiple components to perform the same function thus allowing one component to fail without failing the entire system. Although this duality of devices meets acceptable safety requirements including Federal Regulations, it greatly increases the cost and weight of current rod end bearing designs. In addition, components designed in this way are bulky and require a great deal of space to be mounted within the aircraft.
Therefore, a need has arisen for a method and apparatus for a dual load path rod end bearing and a dual load path spherical bearing that overcomes the disadvantages and deficiencies of the prior art.
An apparatus for a dual load path spherical rod end bearing comprises a bearing race and a bearing ball. The bearing race comprises a bearing race first half and a bearing race second half adapted to interface with the bearing race first half to form a bearing ball cage. The bearing ball is rotatably caged in the bearing ball cage. The bearing ball comprises a bearing ball first half, and a bearing ball second half adapted to interface with the bearing ball first half.
An apparatus for a dual load path spherical rod end bearing comprises a bearing race and a bearing ball. The bearing race comprises a bearing race first half having an internally and externally threaded half coupling shaft, and a bearing race second half adapted to interface with the bearing race first half to form a bearing ball cage and having an internally and externally threaded half coupling shaft. The bearing ball is rotatably caged in the bearing ball cage. The bearing ball comprises a bearing ball first half, and a bearing ball second half adapted to interface with the bearing ball first half.
In another embodiment of the present invention, a dual load path spherical rod end bearing comprises a bearing race, a bearing ball, a collar and a coupling shaft. The bearing race comprises a bearing race first half comprising: a first end plate, at least one projection extending from the first end plate, and an internally and externally threaded half coupling shaft; and a bearing race second half adapted to interface with the bearing race first half to form a bearing ball cage and comprising: a second end plate, at least one projection extending from the second end plate to interface with at least one projection extending from the first end plate, and an internally and externally threaded half coupling shaft. A bearing ball is rotatably caged in the bearing ball cage. The bearing ball comprises a bearing ball first half, and a bearing ball second half adapted to interface with the bearing ball first half. A collar having internal threads receives the external threads of the coupling shaft, and an inner shaft of the collar receives the internal threads of the coupling shaft.
A technical advantage of the present invention is that both the dual load path spherical bearing and the dual load path bearing race incorporate a bearing ball split into two cooperating halves and a bearing race split into two cooperating halves. The advantage of the invention is that the bearing ball first half may transmit a force integral with or independent from the bearing ball second half. This redundancy feature minimizes catastrophic failure of the assembly if either the bearing ball first half or the bearing ball second half fails. Similarly, the bearing race first half may transmit a force integral with or independent from the bearing race second half, thus preventing catastrophic failure of the assembly if either the bearing race first half or the bearing race second half fails. In addition, the rod end bearing of the present invention maintains a load path if only one bearing ball half and one bearing race half are mated.
The dual load path spherical rod end bearing contains further technical advantages. The dual load path spherical rod end bearing comprises a coupling shaft split into two cooperating halves. These coupling shaft halves are threaded as a conventional rod end bearing, but are additionally threaded on the inner bore of each half shaft. This allows for the attachment of a dual load path xe2x80x9cshaft in shaftxe2x80x9d design. That is, the bearing coupling shaft operates to receive an outer collar coupled to the outside diameter of the bearing coupling shaft, and an inner shaft coupled to the inner bore of the bearing coupling shaft. These components may transmit a force integral with or independent from each other such that if either the collar or the inner shaft fails, a load path is maintained through the non-failed component. In addition, in one particular embodiment of the present invention, each bearing ball half has an independent bushing such that if either bearing ball half or bushing fails, a load path is maintained through the non-failed bearing ball half and bushing.
Another technical advantage of the present invention is that both the dual load path spherical bearing ball and the dual load path bearing race comply with acceptable safety regulations, while reducing the associated cost, weight and bulk of previous complying spherical rod end bearings.